Electrical outlet box



2 Sheets-Sheet l F. J. KENNEDY ELECTRICAL OUTLET BOX 'March 6, 1951 Filed June 1, 1948 F. J. KENNEDY ELECTRICAL OUTLET BOX March 6`\l 1951 2 Sheets-She'e' 2 Filed June l, 1948 YVENTO anlCJfCzzgl @am 13 Wm Patented Mar. 6, 1951 UNITED ASTATES rl'rizri'rv OFFICE ,2,544,232 j "ELECTRICAL OUTLET 'BOX Application Junel, 1948, Serial No. 30,221

This inventionrelates to ian electrical `outlet 1 Claim. (Cl. 22d-3.94.1)

and junction box, hereinafter ydesignated simply as an outlet box.

One'object ofthe invention is to providea fabricated outlet box which is rmly integrated and sturdy in its structure, and particularly .in the tightness and security with which the bottom of the outlet box is integratedwiththe other outlet box structure.

Another object of the *invention lis -to `provide a fabricated outlet 'box possessing the properties .abovenoted which is integrated-Whollyfby means .of the substance 'of L'its primaryfstructuralparts, .Without 'welding Ior lsoldering and-without the fuse `of added `'connecting parts or pieces.

Another obj ect Yoff'theiinventionis to 'provide an outlet box of such simple `structure candi-to vproduce lsuch box by ka method so'simp'le `andrdire'ct lthat the outlet boxis expeditiously and economically manufactured and that rwas'te of :metal 1in scrap is minimized.

A still further object Yof theinyen'tionisftorprovide an outlet-box having lthe .above Vnoted properties which also has sharply defined contours rand the wall structure of -which presents sextended plane surfaces connected "on lrelatively shortradii Electrical outlet b'oxes'areused in fgre'atmumbersjare subjected to Arough handling iin'installation andare subjected when installed "to #jars and vibration which may be fof great severity. The `bottom Wall -of 'an outlet fbox 'Ilies .against 1a building wallor other structure directly fzto mount the outlet box and the boundingA walls 'Offthe outlet box support-at their knockouts electrical devices of `various sorts,-so :that there :are exerted y on a mounted outlet box forces tending to sepavrate or loosen the connectionbetween 4the -bottom walland other walls of the outlet box. `It is desirable that the bottom wall .o'f'ithe outlet box should vlie fdea'd against ka planesurface on which the outlet lbox is mounted, Awithout tendency to rock on'suchfsurf-ace.

All the above objects Vare attained :andI all fthe above requirements are met by the youtlet 'box of my invention. All vprior artV outlet boxes ifail in some one or `more properties to attain 'those objects or to meet those requirements. Outlet boxes made by deep-drawingfoperations fare :of course Well integrated but the walls of l.such'fa box meet on long radii, the greater proportion of the Wall area is not truly plane, thel deepdrawing 4is relatively slow and expensive land the scrap loss is lhigh. In `prior f-abricated`boxes the connection between Ithe "bottom 'wall -and 'the Y.

bounding Walls of thebox `is relatively loose and insecure, or lis eiectedby weldingfas is also the integration oi 'the bounding wall structure, with consequent increase =intime fandfequipment :neoessarily 'employed l"in f'making 'fthe outlet box.

In a preferred embodiment, yany ioutletibox longer or side walls and shorter or end 'walls bent from fa single length of preformed v,metal `strip E'the'.ends of which are united by an inter.:- locked, weldless, joint. Retainer feet for engagement by a separately formedbottom wall or plate are punched out of the substanceof the side and end walls .in spaced relation with the adjacent edges thereof. The walls are scored Vwith a groove parallel to the bottom edges of the walls and .spaced to forma line of prepared flexure spaced .by 'the thickness of the bottom wall .from

a line dened by the plurality of retainer feet. The .bottom wall is clinched against the Aretainer feet by clinching `flanges Which are bent over at the scoreline and brought into clinchingfengagement with -a bottom walliorced against theretainer feet.

The method of makingmy :outlet boxinvolves 'fprogressivelyforming the sideand end walls .by :unwindingrstrip of suitable width from acoil;and

scoring `it parallel to one `edge while forming vnotches'spaced along said edge. I stamp out the bottom retainer .feet and the customary knockouts in successive stages, sever the proper length of strip. along a dovetail shear line, then bend the length to vbring .its ends together Aand assemble the yseparately formedbottom plate With the side dimension.

Fig. IIIisfa plan vView of the side and end wall structure .of the outlet box following the bend- Ling and integration of a'prepared lpiece to pro- -videthe ambient Wall structure of the box.

Fig. IV isa longitudinal section through the Abox taken in inverted position of the box in the plane 'of .section line IV-IV of Fig. III. Fig. V is a View similar to Fig. IV showing mar- ,.ginal bottom portions, kor clinching flanges, of the-sideand end'walls partly bent over marginal regions ofthe .bottom Wall or plate of the outalet box.

lFig. VI is a View similar to Figs. IV and V showing the marginal portions, or clinching ilanges,

fof `the side and end Walls in bottom-clinohing position.

VFig. 'VII is a sectional detail View on an enlarged scale,.takenintheplaneet the sectioniine *lVII--AVII-of Fig. `Lfillust-rating the structure cfa piece lprepared for the bounding wall structure of the box before its formation and integration into such structure.

Fig. VIII is a fragmentary sectional vieW taken in correspondence to the section and scale of Fig. VII but illustrating the stage in the integration of the outlet box shown in Fig. V.

Fig IX is a view similar to Fig. VIII but illustrating on an enlarged scale the completion of the operation of integrating the outlet box as shown in Fig. VI.

Referring initially to Figs. I and II of the drawings, metal strip I is unwound progressively and with a minimum of spaced interruptions from a coil 2 mounted in any suitable manner. As unwound, the strip is passed step-by-step through the appropriate instrumentalities of a multislide press which act progressively on successively -presented lengths of the strip.

In the region A closest to the coil, a continuous groove 3 is impressed parallel to one edge 4 (later to be incorporated in the bottom structure of the outlet box) and spaced substantially from the edge. Also V-notches are cut out from the marginal region lying between edge 4 and groove 3.

At the opposite edge of the strip 6 (later to be the upper edge of the outlet box) marginal material is cut away in regions indicated at 'I to leave spaced ears or lugs 8.

In the next operation a piece of strip i corresponding in dimensions to the length A, the action on which has been described, is dened. In the second action of the press holes 9 are punched in lugs 8. Also the length I of the strip, which may be now considered as a prospective piece B, is defined by transverse lines of severance II. In this action knockouts I2 are pressed from regions of the piece which ultimately are to serve as the longer or side walls of the outlet box, and similar knockouts I3 are pressed in the regions which are ultimately to form the shorter or end walls of the outlet box. The groove 3 is deepened and a line of retainer feet I4 is defined and the retainer feet are partially pressed from the substance of the strip to extend on the same side of the strip as the groove 3 in a line parallel to the groove and spaced inwardly from it a distance which is regulated by the desired thickness of the bottom plate for the outlet box which is subsequently to be applied.

In the next action the length of strip is formed into a knockoi piece C. In that piece the lines of severance I I, which are of dovetail formation and which had been slightly impressed in the strip, are made deeper and as shown one of those lines of severance stands as a free dovetail edge because of the succeeding action in which a piece is knocked olf and formed. It should be noted that in each piece the dovetail ends formed at the lines of severance match, inasmuch as the dovetail tangs and notches at the leading end of each piece have been formed with complementary notches and tangs at the trailing end of the next preceding piece. In piece C retainer feet I4 are fully formed, being severed to provide spaced planar slits along a line adjacent groove 3 inwardly of the adjacent edge of the piece C, and deflected into a position and form in which a portion Illa of each of the feet stands parallel to the body of the strip and presents a free edge or abutment I4b substantially perpendicular to the plane of the strip.

In the above noted successive actions the three lengths ofstrip A, B and C are acted on simultaneously as the strip is advanced step-by-step and for this reason the three lengths A, B and C are shown in Fig. I as simultaneously existing, the lengths A and B being'shown in fragmentary manner and the nal or knockoff piece C being completely shown. There is also a fourth length simultaneously acted on in the press, such length which is a piece similar to piece C, has been severed and formed into the bounding wall structure of the outlet box. Relating this nal action of the press to piece C, that piece next is knocked off and is formed by dies into the bounding wall structure of the outlet box, as shown in Figs. III and IV. In this action knockouts I2 and I3 which have projected from the plane of the strip are forced back into line with it, and lugs 8 are bent over to a position at right angles with the plane of the walls from the edges of which they extend. The matching dovetails at the opposite ends of the piece are brought together and are forced into interlocking relation with each other to form an interlocked joint. The marginal regions of the strip lying between edge 4 and the score line are shaped with the remainder of the Wall portions with which they are coextensive to provide a plurality of upstanding anges separated by the notches 5.

Referring particularly to Figs. IV, V and VI of the drawings which illustrate the formation of the outlet box, Fig. IV shows the bounding wall structure of the outlet box standing in inverted position with score lines 3 and retainer feet I4 extended completely around the box and with the interval between the upper edges of the retainer feet and the score line clearly dened. Clinching flanges lying beyond the score line remain in upstanding position continuous with the plane of the walls. In this position and relation of its elements the partially fabricated outlet box is placed in a suitable press and bottom plate l5 is applied to rest on retainer feet I4.

In Fig. V bottom plate I5 is shown in a position occupying the space between the upper edges of the retainer feet and the groove. Clinching anges I6 have been bent over by the press to a position in which they stand at an angle of 45 or slightly more with the planes of the bounding walls, marginally to overlie the bottom plate.

In Fig. VI the outlet box is shown in completed form as effected in the next pressing operation. In this final stage bottom plate I5 is tightly and securely engaged with the side Walls solely by the clinching effect of fianges I6 which are forced downwardly into full clinching position on marginal regions of the bottom plate against the solid backing provided by the plurality of upstanding retainer feet I4.

It should be understood that the integration of the bottom wall or plate With the bounding walls of a fabricated outlet box presents a serious problem. If such bottom be integrated in the assembly by welding it to the bounding walls the welding is performed in separate welding apparatus adapted to the purpose, and the operation by consuming a considerable amount of time in handling and in making the Weld adds a large item of cost to the manufacture of the fabricated box. There is substantial scrap loss by reason of imperfect welding and if the box be dropped or forcefully struck there is danger of breakingl the Weld. The expedient of using lugs, such as the attachment lugs 8 of the applicants outlet box, also is unsatisfactory. While those lugs are suitable for the attachment of a cover, or the like, an attempt to secure a bottom plate or wall in position by engaging it between alternately positioned lugs has proven inadequate, because it permits play between the bottom plate of the outlet box and its bounding walls and progressive loosening with handling and under jars or vibration. The attachment of the bottom plate by screws or rivets also is unsatisfactory.

In engaging the bottom plate of the outlet box to the bounding walls by a pressed engagement the problem tnus is to effect a clinching which is sufficiently secure and tight to hold the bottom plate permanently and immovably in position. In my outlet box such clinched engagement is obtained by providing a rm resistant backing at one side of the plate against which backing the pressing operation can be performed, and to bring the engaging flanges which secure the bottom plate against such backing into full clinching position. The parts by which that effect is obtained are shown in detail in Figs. VII, VIII and IX of the drawings.

Thus considering Fig. VII it will be seen that foot Ill presents its edge Mb in a plane at right angles to the plane of the strip and that it is initially severed along that edge and deflected away from the plane of the wall toward what is to be the cavity of the outlet box, to provide a seating surface or abutment' |412 in a region which is removed from the nearest edge of the strip. Foot lli thus is not of the nature of an ear or lug formed at the edge of the wall, but the foot has a rigidity attendant upon its location and the fact that it has a substantial reach Ida extended parallel to the wall. By using a plurality of feet I4 of relatively smallsize a rigid backing which is capable of sustaining great pressure is provided as a clinching seat for bottom plate l5. Further referring to Fig. VII, it will be seen that groove 3 is spaced from both the edges Mb of feet I4 and from the extreme edge li of the strip.

Fig. VIII shows the condition preparatory to the clinching action. In this gure of the drawings bottom plate I5 rests on the edges Mb of the feet and against the inner surface of the bottom wall to occupy space between the edges I 4b and groove 3. Clinching flanges I6 standing outwardly of groove 3 and separated by V-notches 5 have uninterrupted reaches extending each along one of the four bounding walls of the outlet box.

Fig. IX shows bottom plate I5 securely clinched against retainer feet i4 by folding clinching flanges I6 at grooves 3 and pressing them forcefully against marginal regions of bottom plate I 5, which in turn is forced nrmly against the plurality of retainer feet I4. In this action, which preferably is effected in two stages as is illustrated in Figs. V and VI of the drawings, groove 3 performs an important function. This is to cause the clinching flanges to be folded cleanly and sharply against the adjacent edges of the bottom plate as well as to facilitate the bending. Thus the edges of bottom plate l5 being received in the space provided by groove 3, a clean positive clinching joint is made, securely and immovably to integrate the bottom plate with the bounding walls of the outlet box.

As explained, the elements shown and described and illustrated in detail in Figs. VII, VIII and IX, result in the formation of a firmly integrated outlet box which possesses all the advantageous features of a fabricated outlet box in conjunction with all the advantageous features of a deep-drawn outlet box. Thus the integration of the box is such that the bottom is held securely and immovably with the bounding walls against rough handling and the jars and vibrations of service. The outlet box has a bottom structure which rests nat and dead on a plane Surface and the radii along the edges of the bottom and at the junction of the side and end walls of the box are so short as to give the outlet box a sharply dened contour and provide a maximum of space within the box. The outlet box is manufactured by a method which is both rapid and inexpensive inasmuch as it avoids the relatively unsatisfactory modes of integrating the bottom of the outlet box with the bounding walls which previously have been practiced. The box as a whole is Weldless, the entire integration being effected by the substance of its primary structural parts without welding or soldering and without the use of added connecting parts or pieces. The scrap loss is very low, both in minimizing the metal which lis cut away in preparing a structural `piece and in forming it into the bounding wall structure of the outlet box and in the scrapping of completed or partially completed outlet boxes because of defects. In the later instance great advantage is presented over the manufacture of outlet boxes by a deep-drawing operation in which the scrap loss is high because of the high proportion of defective boxes produced by that operation.

Although I have illustrated and described only a preferred embodiment and practice of the invention, it will be recognized that changes in the structural detail and procedure disclosed may be made without departing from the spirit of the invention or going beyond the scope of the appended claim.

I claim as my invention:

In an electrical outlet box comprising a onepiece bounding wall structure and a bottom structure, the combination of a plurality of retainer feet, said feet being formed by spaced planar slits in the wall structure spaced inwardly from one edge thereof with the material of the Wall structure on the side of the slit opposite said edge being displaced inwardly of the space bounded by said wall structure forming outwardly facing abutments, a separately formed bottom plate lying against the abutments of said feet, and clinching anges of one piece with the said bounding Wall structure lying marginally against the said bottom plate in opposition to the said retainer feet in cooperative clinching relation with respect to said feet and the said bottom plate.

FRANK J. KENNEDY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 180,329 Duc, Jr. July 25, 1876 607,989 Erickson July 26, 1898 781,778 Leppert Feb. 7, 1905 782,417 Robb Feb. 414, 1905 1,072,009 Keefe Sept. 2, 1913 1,428,195 Wahl et a1 Sept. 5, 1922 1,447,600 Olevin Mar. 6, 1923 1,471,340 Knight Oct. 23, 1923 1,971,908 Fullman Aug. 28, 1934 2,076,342 Hildebrandt Apr. 6, 1937 FOREIGN PATENTS Number Country Date 29,162 Great Britain 1911 

